On 1 July 1569, the union of the Polish Crown and the Grand Duchy of Lithuania was established in Lublin during a session of the general Sejm, known as the Union of Lublin. It continued until the end of the 1700s, thus becoming one of the most durable of such alliances in European history. What do you think were the key factors determining its longevity?

Leaving administration and law in the Crown and the Grand Duchy of Lithuania separate allowed the nobility of both countries retain their own identity, thanks to which the union of both countries did not have any serious resistance among Polish elites.
The combination of the Polish and Lithuanian potentials resulted in a military power not to be broken by the neighbouring states.

Voting results for previous surveys.